| # AOT Snapshot Size Profiling |
| |
| The VM supports profiling the size of AOT snapshots by leveraging the object-graph based file format introduced by V8. |
| |
| ## Recording a profile |
| |
| To generate a snapshot profile, simply pass the `--write-v8-snapshot-profile-to=<filename>` flag to `gen_snapshot`. |
| The profile will be written in JSON format to the requested file. |
| Make sure to use the ".heapsnapshot" extension for the file to open it in Chrome DevTools. |
| |
| ## Examining a profile in Chrome |
| |
| Open Chrome DevTools, navigate to the "Memory" tab, right-click on the "Profiles" panel, click Load..." and select the snapshot profile file. |
| See https://developers.google.com/web/tools/chrome-devtools/memory-problems/heap-snapshots for details on how to use the tool. |
| |
| ## Examining a profile programmatically |
| |
| A Dart library to parse the snapshot profile format is provided in `pkg/vm/lib/v8_snapshot_profile.dart`. |
| The `dart2js_info` package has some useful code for calculating retainers and other graph statistics. |
